In reference 10 of his Nobel Prize acceptance speech, Hoffmann states that the term "isolobal" was introduced in reference 1e, "Elian, M.; Chen, M. M.-L.; Mingos, D. M. P.; Hoffmann, R. (1976). "Comparative bonding study of conical fragments". Inorg. Chem. 15 (5): 1148–1155. doi:10.1021/ic50159a034.", but that the concept is older.